1. Field of the Invention
The present invention relates to a system and method for accessing data stored on non-host systems with multiple non-host file systems and, in particular, to a system and method for accessing non-host data via host application programs using record-based access methods.
2. Description of the Related Art
Application programs in the host environment frequently use record-based access methods. For example, the IBM VSE/ESA host operating system uses the record-based access method Virtual Storage Access Method (VSAM) to access data. VSAM does not provide information relating to the internal structure of the data; the application itself must provide this information. Furthermore, host data is stored in EBCDIC (Extended Binary-Coded Decimal Interchange Code) format. EBCDIC is a binary code for alphabetic and numeric characters that IBM has developed for its larger operating systems. In each EBCDIC file, each alphabetic or numeric character is represented by an 8-bit binary number. In contrast to the VSAM data access method, data access methods for non-host file systems use a table row providing information about the structure of the data to be accessed. The application itself does not provide any information relating to the structure of the data to be accessed. Furthermore, data of non-host systems is stored in ASCII format. ASCII is the most common format for text files in computers on the Internet. In an ASCII file, each alphabetic, numeric, or special character is represented by a 7-binary digit number. Therefore, the VSAM access method is not compatible with any access method for non-host systems.
Host systems use a great number of applications, which have been developed over a long period of time. New technologies like Internet technologies or e-business applications are mainly based on UNIX platforms using non-record-based access methods. Therefore, the major growth in the future is not located in the host system environment using proprietary record-based access methods like VSAM, but in the UNIX or Linux environment using non-record-based access methods. In order to protect the investments in the host sector, it is desirable that the host applications can work without any change with data stored on the new platforms.
Furthermore, VSAM data must be transferred from the host environment to the UNIX or Linux environment in a relatively simple way.